The British prime minister is touring Europe to make his case for reform, without which he warns a British exit from the union might be necessary. But Germany could be more friend than foe if Cameron's reforms are constructive.

Paris — British Prime Minister David Cameron has been viewed warily on his two-day tour of key European capitals. While Mr. Cameron frames his trip as a campaign to get “a better deal for Britain” from the 28-member European Union, many see him as potential architect of the dismantlement of Europe and its basic principles, like the free movement of people across the EU.

But at his last stop in Berlin today, he might be able to set a more positive message – that a better deal for Britain is a better deal for Europe. And if that's the case, he could find Germany to be an ally, not an obstacle.

At a time when Euroskeptics are appealing to voters across a weary EU, Mr. Cameron is seeking to sell himself not as the political leader who is yet again testing the fate of the EU, but who is offering a solution – creating a union that works better and restores citizens’ faith in it.

Cameron’s referendum on EU membership, which is to be held before the end of 2017, turned from hypothetical to reality after his shock majority win in British elections this month. He had long promised a referendum on EU membership before 2017 if he won, and the Queen’s Speech on Wednesday sealed that as part of the Conservative agenda. Now he is on a whirlwind trip to get his allies on board with ideas that range from British veto power on EU regulations to restrictions on welfare for migrants.

His stops have proven illustrative of the array of sentiment he faces. The Netherlands, his first visit, agrees with his push for European reform, especially for a more competitive and efficient EU.

France is more skeptical. Although French President François Hollande at a press conference Thursday spoke of the mutual interest of both nations to keep Britain in the EU, Foreign Minister Laurent Fabius told French radio before Cameron’s arrival that he thought the referendum itself was dangerous. “Obviously, the British population, who have grown accustomed to hearing ‘Europe is a bad thing. Europe is a bad thing,’ the day they’ll be consulted, there’s a risk they’ll say, ‘You told us Europe is a bad thing.’”

And Poland, from which thousands of migrants headed to Britain when it joined the EU, gave it a flat-out no in terms of his plans to restrict welfare benefits. Polish Prime Minister Ewa Kopacz “expressed strong opposition to solutions that could lead to the discrimination of Poles or other EU citizens working legally in Great Britain,” according to a statement released by her office. “By doing so she defended one of the core principles underlying the single market in the European Union.”

But it is in Germany today that Cameron might find its most receptive ally. First of all, while Britain leaving would be a blow to all of Europe, perhaps it would be the biggest loss for Germany. Michael Wohlgemuth, an economist and director of the Berlin-based think tank Open Europe, says that a Brexit would cost Germany an ally on the side of open markets and free trade. A British exit would reduce the size of the EU's free-market bloc to a point where it could no longer veto protectionist policies pushed by more interventionist nations of Europe – an unpalatable outcome for Germany.

A Brexit would also skew power and responsibility to Germany even further, both of which the European powerhouse prefers to remain spread for fear of having to manage crises like that in Greece without allies.

German Chancellor Angela Merkel has made clear before that she will only go so far to prevent a Brexit. Germany is wary of major treaty changes. But it is here that Cameron might be able to sell his message that Germans benefit from British actions – not that Cameron is just in this to appease an intolerant electorate or win special privileges for the UK.

“As a charm offensive, I think it could work if he really frames it as reform for the EU as a whole,” says Mr. Wohlgemuth. Some of what Cameron has focused on – the bloc’s crisis of competitiveness and bringing it closer to its citizens – are “things pretty much everyone would accept. On the basic principles there is some consensus.”